1. Field of the Invention
The present invention generally relates to a method of controlling detouring in an integrated network and a communication device based on such a method, and particularly relates to such a method and a communication device where the integrated network is comprised of an ATM (asynchronous transfer mode) network that integrates various media and communications.
2. Description of the Related Art
Detour control in an ATM integrated network is defined by PNNI (private network-to-network interface) protocols, which establish an appropriate detour route when node failure, communication-path failure, and/or communication-path congestion make communication impossible along an original route.
At a port having the PNNI protocols assigned thereto, metric information is defined on a service-category-wise bases so as to be reported to other nodes, such metric information including control weights, cell-transfer delays, cell-delay fluctuations, etc. Such information is reported by using PTSPs (PNNI topology state packets) to other nodes, where GCAC (generic connection admission control) is performed based on the received information. Here, the GCAC selects a route.
Technological development and market progress of the ATM technology have led to an emergence of an ATM integrated network in which conventional low-speed data lines, high-speed data lines, frame relay lines, audio communication lines, etc., are connected via ATM lines. Such an ATM integrated network includes various media devices, and transfers data between terminal devices.
In the following, a detour function will be described.
FIG. 1 is an illustrative drawing for explaining a detour function in an ATM network.
FIG. 1 shows a situation where a route RT1 and a route RT2 are functioning properly. When a CES (circuit emulation service) terminal CES1 that renders a service for providing a dedicated-line like path in the ATM network transfers data to a CES terminal CES3, the data travels along a route from CES1, AWN(ATM WAN node)-l, AWN-2, AWN-3, to CES3. Also, when an FR (frame relay) terminal FR1 that achieves high-speed data transfer by using simplified protocols transfers data to an FR terminal FR3, the data travels along a route from FR1, AWN-1, AWN-2, AWN-3, to FR3.
FIG. 2 is an illustrative drawing showing a situation where a failure occurs in the ATM network of FIG. 1.
When an ATM line between AWN-2 and AWN-3 suffers a failure as shown in FIG. 2, the data from CES1 to CES3 cannot take the route RT1 shown in FIG. 1. In response, a route is changed to a route RT3 which extends from CES1, AWN-1, AWN-2, a public network, AWN-3, to CES3, and the data travels along the route RT3. By the same token, the data from FR1 to FR3 cannot take the route RT2 shown in FIG. 1. In response, a route is changed to a route RT4 which extends from FR1, AWN-1, AWN-2, the public network, AWN-3, to FR3, and the data travels along the route RT4.
Usage of the network varies depending on a type of media. For example, even when a given frequency band of the public network is set aside for use by the FR terminal FR1, the FR terminal may not be using this frequency band at a given point of time.
FIG. 3 is an illustrative drawing for showing an alternative route in the ATM network of FIG. 1.
In FIG. 3, a route RT5 connecting between AWN-1 and AWN-3 via AWN-4 is functioning normally and available. In this case, AWN-1 should select the route RT5 rather than the route RT4 of FIG. 2 since the route RT5 provides a communication path within a private network whereas the route 4 incurs charges for use of the public network. When a failure occurs on the ATM line between AWN-2 and AWN-3, however, a route is changed to the route RT4 as a matter of course in the conventional scheme, offering no other option to select an optimum detour route.
Accordingly, there is a need for a method of controlling detouring in an integrated network which allows a detour route to be selected according to the type of media, and, also, there is a need for a communication device based on such a method.
Accordingly, it is a general object of the present invention to provide a scheme for controlling detouring in an integrated network such as to achieve the needs described above.
It is another and more specific object of the present invention to provide a method for controlling detouring in an integrated circuit which allows a detour route to be selected according to the type of media.
In order to achieve the above objects according to the present invention, a method of controlling detouring in an integrated network which includes communication devices includes steps of registering routes at a communication device connected to terminal devices of respective media types such that the routes include a main route and a detour route with respect to each of the media types, and establishing a connection along the detour route registered for a media type upon finding unavailability of the main route registered for the media type when a call of the media type is requested from one of the terminal devices.
It is yet another object of the present invention to provide a communication device which can select a detour route according to the type of media.
In order to achieve the above object according to the present invention, a device for communication in an integrated network, connected to terminal devices of respective media types, includes a detour-information-storage unit which stores routes registered therein such that the routes include a main route and a detour route with respect to each of the media types, and a detour-control unit which establishes a connection along the detour route registered for a media type upon finding unavailability of the main route registered for the media type when a call of the media type is requested from one of the terminal devices.
Other objects and further features of the present invention will be apparent from the following detailed description when read in conjunction with the accompanying drawings.